DIRECTIONS OF ARRIVALS OF GREAT BLUE HERONS (ARDEA-HERODIAS) AT NESTSWITH LARGE CHICKS NEAR MONTREAL, QUEBEC

We studied the arrivals of Great Blue Herons (Ardea herodias) breeding at the Ile Saint-Bernard heronry near Montreal, Quebec. A total of 42 nests were monitored during the daytime. Overall (i.e., for all fligh t directions), the distance separating the colony from the potential f eeding areas seems to have been the single most important factor in th e herons' choice of feeding sectors. Date, wind direction, and water l evel had a slight influence on the use of feeding areas in this riveri ne system. Flight directions varied slightly according to these variab les during the sampling period. Other variables such as wind speed, ti me of day, cloud cover, and rain had less influence on the distributio n of flight directions. Many breeding pairs used only one or two secto rs in particular while feeding their brood. We suggest that in natural environment contamination studies, the faithfulness of certain pairs to specific feeding sectors could help to identify the origin of the c ontaminants found in the tissues of sampled birds.